1. Field of the Invention
The present invention relates to an electronic blackboard which is capable of outputting image data, which is read from a screen, to a removable external storage medium. In this application, “electronic blackboard” refers to an electronic board on which information can be written. The board is not necessary black, and may be, for example, a whiteboard.
2. Discussion of Related Art
An electronic blackboard is known which is capable of reading an image, which is written on a screen using a writing material(s), as image data using an optical sensor, such as a CCD, and which is capable of printing out the image data using a printer. The electronic blackboard is used in companies and research institutes at meetings, for instance.
Recently, an electronic blackboard has been made available which is capable of outputting read image data not only to a printer but also to an external storage medium, such as a flash memory.
For example, Japanese Laid Open Publication No. 2004-015371 discloses an electronic blackboard which has an external interface. According to this publication, image data read from a screen is transmitted to an external terminal via the external interface.
In a conventional electronic blackboard, the writing on the screen may be light due to worn-out writing materials and/or differences in writing pressure. In this case, the read image data is also light, which causes a problem whereby a printed image is light or unprintable. In addition, a conventional electronic blackboard may be unable to capture useful image data because the read image data has an imperfection.
Japanese Laid Open Publication No. 2000-244735 discloses an electronic blackboard, which enables arbitrarily setting a binary threshold for each read image data to prevent a printed image from being light or becoming unprintable, when a density control is executed.
In a conventional electronic blackboard, however, an operator cannot accurately confirm whether or not image data has an imperfection, when the operator attempts to output the image data to an external storage medium.